From German Patent 31 28 111, it is known that a fiber reinforced sleeve-shaped band of rubber can be pushed on rollers which can be separated from each other and which are rotatably journalled about their longitudinal axes, in order to thereafter cut individual V-belts with one or more knives. With such a cutting machine, thin-walled V-belts having the same dimensions can be cut from each closed band; however, it is disadvantageous that the manufacturing sequence for producing such belts can be automated only to a very limited extent. Finally, the V-belts must be released of tension on the rollers after cutting the closed band of rubber into a plurality of individual V-belts and, after one of the roller stands is pivoted away, the V-shaped belts must be removed from the rollers. Only thereafter is the apparatus again ready to be supplied with a closed band and the belts are available for further processing in the form of a heap of 20 to 100 pieces as a rule.
Thin-walled belts having a rectangular cross section cannot be produced on this apparatus since deformations result secondary to a clamping device pressing the closed band against a holding shoe. These deformations do not permit precise belt dimensions at a right angle cross section (column 4, starting at line 66).
Furthermore, a V-belt cutting machine having cantilevered drive and tension rollers is known from U.S. Pat. No. 4,586,410 incorporated herein by reference. Here, the closed band is pushed over both rollers and tensioned. The closed band experiences a component of movement by means of a pivoting movement of the tension roller about a pivot axis lying perpendicular to the roller axis. The component of movement drives the closed band during its rotation about the two rollers against a roller stop provided with a force sensor. A control arrangement connected to the sensor compares the striking force of the closed band to a desired force set previously. If this desired force is reached by means of the further pivoting of the tension roller, then a knife cuts a belt having a predetermined width from the closed band. The cut off belt is taken up by a collecting device and removed to other processing stations. The closed band is brought into position for cutting the next belt by a change of the pivot angle of the tension roller and by a forward displacement of the stop equipped with the sensor.
The periodic removal and transporting away of the belt just cut constitutes a great advantage in that the belt production process can be partially automated. However, in contrast to this advantage, there is the disadvantage that with such an assembly only comparatively thick closed bands of rubber can be cut into belts having the same dimensions. The cause of this is that the stop applies a small force to the closed band which leads to a local deformation at the point of application of the stop at the rearward end face of the closed band. Furthermore, this stop force effects a compressive deformation of the overall closed band which becomes that much greater the thinner the closed band of rubber is.
Since the closed band of rubber tensioned between the rollers exhibits a spring-like behavior when a force is applied to its end faces, the compressive deformation along the closed band becomes ever more noticeable at the opposite end the narrower the remainder of the closed band is which remains because of the continuous cutting off of belts.
This has the consequence that thin belts can be cut only with a pregiven width tolerance which, as a rule, is not acceptable for rectangular belts. In contrast, belts which are cut from a relatively thick closed band and which are therefore less sensitive against the stop deformation can be produced with great use on this equipment. For the production of raw-edged V-belts too, the disadvantages of the equipment described are not significantly noticeable since only the waste piece cut by the knives has various sizes.